The role of interface in microbubble ozonation of aromatic compounds

Chao Wu; Pan Li; Shengji Xia; Shuo Wang; Yue Wang; Jun Hu; Zhengqian Liu; Shuili Yu

doi:10.1016/j.chemosphere.2018.12.174

The role of interface in microbubble ozonation of aromatic compounds

Chemosphere. 2019 Apr:220:1067-1074. doi: 10.1016/j.chemosphere.2018.12.174. Epub 2018 Dec 26.

Authors

Chao Wu¹, Pan Li², Shengji Xia³, Shuo Wang⁴, Yue Wang¹, Jun Hu⁴, Zhengqian Liu⁵, Shuili Yu³

Affiliations

¹ School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, PR China.
² School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, PR China; School of Environmental Science and Engineering, State Key Laboratory of Control and Resource Reuse, Tongji University, 1239 Siping Road, Shanghai, PR China. Electronic address: lipan@tongji.edu.cn.
³ School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai, PR China; School of Environmental Science and Engineering, State Key Laboratory of Control and Resource Reuse, Tongji University, 1239 Siping Road, Shanghai, PR China.
⁴ Shanghai Institute of Applied Physics and Key Laboratory of Interfacial Physics and Technology, Chinese Academy of Sciences, Shanghai 201800, China.
⁵ School of Environmental Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, PR China.

PMID: 33395793
DOI: 10.1016/j.chemosphere.2018.12.174

Abstract

Due to its high mass transfer efficiency, microbubble ozonation has been widely used in water treatment to degrade refractory compounds. Compared to conventional bubbles (diameters larger than 1 mm), microbubbles (diameter less than 50 μm) have special interfacial characteristics that are probably advantageous in ozonation. However, the mechanisms involved are still unclear and therefore our primary aim here was to explore the interfacial effect of microbubbles during ozonation process. Phenol and nitrobenzene degradation by ozone microbubbles and conventional bubbles were carried out across a broad pH range. We found that microbubble decomposition of pollutants was markedly more efficient than conventional bubbles in terms of ozone consumption. Hydroxyl radical scavenger experiments of phenol revealed that the enhancement of microbubble might result from the increase of ozone concentration in interfacial region and a mathematical simulation further proved this synthesis by showing that ozone concentration is not homogenous throughout the reaction medium and forms a steep gradient in the liquid film of microbubbles. As for nitrobenzene, the acceleration of hydroxyl radicals was supposed to be the dominate factor which might be the consequence of high gas concentration in liquid film. These findings shed light on the mechanism of interfacial reaction in microbubble ozonation.

Keywords: Aromatic compounds; Interfacial reaction; Mechanism; Microbubble; Ozonation.